1. Field of the Invention
The present invention relates to telephone dialing circuits. More particularly, the present invention relates to a last number redial validation device for telephone dialing circuits.
2. Description of the Prior Art
Last number redial is a commonly available feature on many of the telephone sets now available to consumers and businesses. Prior art last number redial circuits provide a memory register for storing a last dialed telephone number. If the line of the party called is busy or there is no answer, the number may be redialed by pressing a last number redial key or pushbutton on the telephone set. Such features eliminate the need to redial the entire telephone number. Any other telephone numbers subsequently dialed are stored in the last number redial memory register, thereby replacing previously stored telephone numbers.
A problem with prior art last number redial circuits is that the contents of the last number redial memory register are disturbed by any subsequent telephone dialing. If a telephone number stored in the last number redial memory register requires the dialing of an access code or any other signalling code, that telephone number or portions of that telephone number are modified from the last number redial memory register by such codes.